Control apparatus for synchronous rotary machine enabling suppression of rotor vibration

Abstract

In a synchronous rotary machine such as a synchronous motor, respective values of the number of pole pairs of the rotor and the number of stator slots are predetermined such as to enable drive currents to be passed through the stator windings which suppress specific varying electromagnetic forces that act on the rotor and produce vibration. The drive current of each phase of the motor consists of a fundamental-frequency sinusoidal waveform current having specific harmonic-frequency currents superimposed thereon, the harmonic-frequency currents having angular velocities which are appropriate, with respect to the angular variation velocities of the specific varying electromagnetic forces, for suppressing these forces.

What is claimed is: 
     
       1. A control apparatus for a synchronous rotary machine, the rotary machine comprising a rotor having P pole pairs, where P is a positive integer, and a stator having S slots, where S is a positive integer equal to 3 or greater, the stator wound with stator windings of respective phases;
 wherein 
 designating a prescribed value as a value obtained by multiplying a lowest common multiple K of the number of slots S and double the number of pole pairs P by a positive integer, 
 designating a value obtained by multiplying a sum of the prescribed value and the number of slots S by a mechanical angular velocity of the rotor, and a value obtained by multiplying a difference between the prescribed value and the number of slots S by the mechanical angular velocity of the rotor, as respective suppression-object angular velocities, and 
 designating a first angular velocity and a second angular velocity as respective prescribed angular velocities, the first angular velocity being obtained by multiplying a sum of the prescribed value and the number of pole pairs P by the mechanical angular velocity of the rotor and the second angular velocity being obtained by multiplying a difference between the prescribed value and the number of pole pairs P by the mechanical angular velocity of the rotor, 
 the control apparatus comprises current passing circuitry configured for passing fundamental-frequency sinusoidal-waveform currents through the stator windings, each fundamental-frequency sinusoidal-waveform current having superimposed thereon at least one harmonic-frequency current having an angular velocity equal to a prescribed angular velocity, for thereby suppressing a varying electromagnetic force acting on the rotor and having an angular variation velocity equal to a suppression-object angular velocity. 
 
     
     
       2. The control apparatus for a synchronous rotary machine as claimed in  claim 1 , wherein a harmonic-frequency current having an angular velocity equal to the first prescribed angular velocity, and a harmonic-frequency current having an angular velocity equal to the second prescribed angular velocity, are respectively superimposed on each of the fundamental-frequency sinusoidal-waveform currents. 
     
     
       3. The control apparatus for a synchronous rotary machine as claimed in  claim 1 , wherein the respective values of the number of pole pairs P and the number of slots S are predetermined for ensuring that neither the sum of the prescribed value and the number of slots S nor the difference between the prescribed value and the number of slots S is a positive integral multiple of the number of pole pairs P. 
     
     
       4. The control apparatus for a synchronous rotary machine as claimed in  claim 3 , wherein the number of pole pairs P is 5 and the number of slots S is 12. 
     
     
       5. The control apparatus for a synchronous rotary machine as claimed in  claim 3 , wherein the number of pole pairs P is 7 and the number of slots S is 12. 
     
     
       6. The control apparatus for a synchronous rotary machine as claimed in  claim 1 , wherein the rotor is of hollowed-out configuration. 
     
     
       7. The control apparatus for a synchronous rotary machine as claimed in  claim 6 , wherein the rotary machine is of outer-rotor type and wherein the rotor is of toroidal shape, with the stator disposed within an inner periphery of the rotor. 
     
     
       8. The control apparatus for a synchronous rotary machine as claimed in  claim 1 , wherein the current passing circuitry comprises:
 a memory having stored therein drive current information stored therein expressing the fundamental-frequency-waveform currents as a sinusoidal-waveform signals each having an angular velocity equal to the electrical angular velocity of the rotor and having a signal corresponding to the harmonic-frequency current(s) superimposed thereon; 
 switching elements controllable for passing current through the stator winding of the rotary machine; and 
 operation circuitry configured for controlling the switching elements to pass drive currents through the stator windings in accordance with the drive current information stored in the memory. 
 
     
     
       9. The control apparatus for a synchronous rotary machine as claimed in  claim 1 , wherein the current passing circuitry comprises:
 command voltage calculation circuitry configured for calculating a waveform of a trapezoidal-waveform command voltage and for generating command voltage signals each having the waveform of the trapezoidal-waveform command voltage and varying at an angular variation velocity equal to an electrical angular velocity of the rotary machine, 
 switching elements controllable for passing current through the stator winding of the rotary machine, and 
 operation circuitry configured for controlling the switching elements to pass drive currents through the stator winding in accordance with the command voltage signals.